1. Field of the Invention
The present invention relates to a copying machine having a function of double-face (reflex) copying, multiple-composition copying and parallel-composition copying.
2. Description of the Related Art
Conventionally, some kinds of copying machines having multifunctions including double-face copying, etc. are provided with a sheet-feeding equipment for double-face copying which is disposed below an image forming section. The sheet-feeding equipment for double-face copying is so constructed that a copy sheet having one face onto which an image has been fixed is inverted by a face-inverting sheet supply section or not and then temporarily stocked in a sheet stock section, and that the stocked copy sheet is refed by a sheet refeeding section to the image forming section wherein an image is fixed onto the other face thereof or the copied face thereof.
With the recent office automation, the multi-functioning of copying machine has been required such as enlargement, reduction, continuous-page printing, double-face copying and multiple-composition copying. With the increased multifunctioning of copying machine, the kinds of the size of sheets to be handled are thereby increasing the number of cassettes. On the other hand, the effective utilization of office floor space has become an important issue because of the recent increase of land prices, whereby a copying machine has been required to have a small installation space in order to save floor space.
As a copying machine which reduces installation space and is capable of mounting many cassettes to the machine assembly thereof, a front loading-type copying machine has been developed. In the machine, a plurality of cassettes storing sheets has been mounted to the lower side of the machine assembly in a manner to be taken out of the front, whereby the cassettes do not protrude beyond the machine assembly to make small the installation area of the machine assembly.
In the manufacture of copying machines, copying machines not provided with a function of double-face copying are sometimes manufactured in compliance of the user's request. In this case, from the view point of the manufacture economy, copying machines which are originally so designed as to perform double-face copying are manufactured with a sheet-feeding equipment for double-face copying omitted. Such a copying machine has a problem in that the large space for mounting a sheet-feeding equipment for double-face copying is useless.
In a front loading-type copying machine, the incorporation of a sheet-feeding equipment for double-face copying requires a large mounting space to be prepared in the machine body. This causes a problem in that the maximum number of cassettes mountable in the machine body, which is an element of the multifunctioning, is restricted, thereby impeding the multifunctioning of a copying machine.
The image fixing process in the image forming section of a copying machine is performed in such a manner that a toner image obtained after the developing and transferring processes is meltingly pressed onto one face of a copy sheet by hot heat rollers. Therefore, the process of fixing an image onto one face causes a copy sheet to produce deformation such as wrinkle and curl and to change characteristic thereof. In a sheet-feeding equipment for double-face copying having the above-mentioned configuration, therefore, there arises a problem in that a sheet-feeding error is liable to occur during the process of refeeding a sheet from the sheet stock section. In order to avoid such a feeding error from occurring during the refeeding process, it is required to use expensive copy sheets having special quality in which the above-mentioned deformation and the characteristic hardly occur, thereby causing another problem that inexpensive copy sheets such as those of regenerated paper which have been widely used in recent years are restricted in the use for double-face copying, and multiple-composition copying.